. The animans and man; an elementary textbook of zoology and human physiology. mandi-bles the locust bites off, and with the help of the other parts,chews bits of leaves, green stems, etc. The palpi are be-lieved to be organs for feeling and tasting the food. Drawthe front of the head, naming the different parts. Note that almost the whole outer surface of the body iscovered with a firm, smooth coat, the chitinized cuticle,that is, the horny outer layer of the skin. The skin of the 4 THE ANIMALS AND MAN neck, however, and that at the bases of the legs and wingsis soft. Why is this necessary? N
. The animans and man; an elementary textbook of zoology and human physiology. mandi-bles the locust bites off, and with the help of the other parts,chews bits of leaves, green stems, etc. The palpi are be-lieved to be organs for feeling and tasting the food. Drawthe front of the head, naming the different parts. Note that almost the whole outer surface of the body iscovered with a firm, smooth coat, the chitinized cuticle,that is, the horny outer layer of the skin. The skin of the 4 THE ANIMALS AND MAN neck, however, and that at the bases of the legs and wingsis soft. Why is this necessary? Note that the soft skin ofthe neck is well protected by the projecting saddle-shapedhorny piece on the front thoracic body-ring. Another use ofthe firm cuticle, or exo-skeleton, as it is called, is to affordsolid points of attachment for the many muscles of thebody, the locust having no bones or any kind of internalskeleton. (In a few places there are processes or continua- antennse auditory organocellus : /head fcompound eyej 1^.. ^abdomen , &£-< \ coxa\frocko/nter. -ovipositor tibia star sal segments FIG. 2. Locust, with external parts named. tions of the exo-skeleton projecting internally and these aresometimes called the endo-skeleton.) That part of the body behind the thorax is called theabdomen. Examine the upper side of the first (nearestthe thorax) body-ring of the abdomen, and find two small,nearly circular, thin places looking like little are the hearing organs, or tympana, of the sound-waves striking against these thin tightly stretchedbits of the body wall, set them into vibration, and thesevibrations stimulate a tiny vesicle and nerve-ganglion THE GRASSHOPPER AND THE SNAIL 5 on the inside from which a nerve leads to one of the internalnerve-centers. This is a much simpler kind of ear than wepossess, and the locust probably cannot hear nearly as wellas we can. Note on each side of each abdominal body-ring(except the last) a tiny blackish
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